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2011
Journal Article
Titel
Atomic-scale engineering of future high-k dynamic random access memory dielectrics
Titel Supplements
The example of partial Hf substitution by Ti in BaHfO3
Abstract
Controlled substitution of Hf4+ by Ti4+ ions in thin BaHfO3 was investigated in view of future dynamic random access memory (DRAM) applications. The 50% substitution of Hf ions reduces the crystallization temperature by about 200 °C with respect to BaHfO 3 layers making the BaHf0.5 Ti0.5 O3 layers compatible with DRAM processing. The resulting cubic BaHf0.5 Ti0.5 O3 dielectrics show k90 after rapid thermal annealing at 700 °C which is three times higher than for BaHfO3 at similar temperatures. Leakage current values of 4× 10-5 A/ cm2 at 0.5 V for Pt/ BaHf0.5 Ti0.5 O 3 /TiN capacitors with capacitance equivalent thickness <0.8 nm are achieved. Synchrotron-based photoelectron spectroscopy in combination with nanoscopic conductive atomic force microscopy measurements reveals that the use of high work function electrodes and homogeneous film deposition techniques is crucial for controlling the leakage current.